1. Field of the Invention
The present invention relates generally to image capturing devices, and more particularly to an image capturing device in which a transparent member is provided on the light receiving surface side of an image capturing element (a light receiving element).
2. Description of the Related Art
Image capturing devices using a CCD or a CMOS image sensor as an image capturing element (a light receiving element) have the image capturing element contained inside a package and have a transparent member such as a glass plate on the light receiving surface of the image capturing element so that external light enters the image capturing element through the transparent member as shown in, for instance, Japanese Laid-Open Patent Application Nos. 62-067863 (Patent-Related Document 1), 2000-323692 (Patent-Related Document 2), and 2002-016194 (Patent-Related Document 3).
Patent-Related Document 1 discloses a structure in which: a semiconductor substrate is mounted on leads; the electrodes of the semiconductor substrate are connected to the leads by bonding wires; a glass plate is bonded onto the semiconductor substrate with a transparent adhesive agent; and the semiconductor substrate and the leads are sealed with resin including a black pigment and functioning as light absorbing material with the surface of the glass plate being exposed.
Patent-Related Document 2 discloses a structure in which: a chip having a light receiving part is mounted on a package with leads; a microlens group is bonded onto the chip using resin of a low refractive index; a light transmitting substrate is provided on the microlens group through a color filter; and water-repellent resin is provided on the periphery of the low refractive index resin and the light transmitting substrate.
Patent-Related Document 3 discloses a structure in which: a semiconductor element is mounted on a base body; the electrodes of the semiconductor element and electrode pads provided to the base body are connected by bonding wires; a light transmitting member is provided on the semiconductor element through UV curable resin provided to the pads; and sealing resin is provided so as to cover the entire side surfaces of the semiconductor element, the UV curable resin, and the light transmitting member.
According to the technique disclosed in Patent-Related Document 1, the glass plate is shaped like a rectangular parallelepiped, and sealing is performed by providing the sealing resin around the glass plate. The glass plate has a rectangular parallelepiped shape with its peripheral surface being perpendicular to the upper surface (light receiving surface) of the semiconductor substrate. Accordingly, unnecessary light (light that does not contribute to image capturing) entering the peripheral surface reflects on the interface between the peripheral surface and the resin so as to be likely to enter the light receiving surface (an image capturing area). When the unnecessary light enters the light receiving surface, optical characteristics are impaired, thus causing a flare or ghost.
Further, according to the technique disclosed in Patent-Related Document 1, the glass plate is bonded to the semiconductor substrate with a transparent adhesive agent. On the other hand, according to the technique disclosed in Patent-Related Document 2, the low refractive index resin is interposed between the chip and the microlens group, and its periphery is sealed by the water-repellant resin. Further, according to the technique disclosed in Patent-Related Document 3, a space is provided between the light receiving part of the semiconductor element and the light transmitting member, and the periphery of the space is sealed by the UV curable resin and the sealing resin.
Therefore, according to the techniques disclosed in Patent-Related Documents 1 through 3, when heat is applied to the devices thereof, the transparent adhesive agent in Patent-Related Document 1, the low refractive index resin in Patent-Related Document 2, and the air inside the space between the semiconductor element and the light transmitting member in Patent-Related Document 3 expand thermally, so that the glass plate, the light transmitting substrate, and the light transmitting member receive pressure-induced forces in directions perpendicular to the semiconductor substrate, the chip, and the semiconductor element, respectively. As a result, the glass plate, the light transmitting substrate, and the light transmitting member may be displaced by the forces.
Further, according to the techniques disclosed in Patent-Related Documents 1 through 3, wires are used to connect the semiconductor substrate and the leads in Patent-Related Document 1, the chip and leads in Patent-Related Document 2, and the semiconductor element and the base body in Patent-Related Document 3. The wires are provided by wire bonding. In the case of covering a light receiving area with the glass plate, the light transmitting substrate, or the light transmitting member before providing the wires, it is necessary to avoid contacting the glass plate, the light transmitting substrate, or the light transmitting member with a bonding capillary.
Therefore, it is required to increase the distance between the peripheral sides of the glass plate, the light transmitting substrate, or the light transmitting member and electrode pads to which the wires are connected. Accordingly, it is required to reduce the size of the glass plate, the light transmitting substrate, or the light transmitting member, or increase the chip size of the semiconductor substrate, the chip, or the semiconductor element. However, if the glass plate, the light transmitting substrate, or the light transmitting member is reduced in size, light reflected by its end faces is likely to enter an image-capturing area so as to hinder optical characteristics. On the other hand, an increase in chip size works against the size reduction of image capturing devices.